1. Field of the Invention
This invention relates to a removable locking device to hold and secure the connection between typical nut type end fittings on two fluid transmission lines being detachably joined together.
2. Background
Fluid transmission lines, such as those carrying reactive gases used in certain semiconductor manufacturing processes, are often vulnerable to leaks or breakage induced by stress from vibration, twisting, temperature change or other environmental conditions. This frequently results in significant downtime, costly repairs and loss of production.
Standard, detachable nut type fittings such as, but not limited to those supplied by Cajon Company, Macedonia, Ohio and C.G.M.I., France, rely principally upon friction and threaded type connection to achieve and maintain tight, leak proof seals which are generally resistant to significant leakage or breakage. Experience has shown that such connections do fail, under continuous use, from vibration, line twisting and temperature change, often enough to affect significantly the above mentioned industrial operations. Experience has also shown that the failure occurs most frequently at the union of the lines, due to loosening of the detachable, nut type connecting fittings.
Review of the patent literature indicates that there are many lock type devices designed to hold a variety of nut type end fittings together. However most of them are of special, often complicated design, requiring customized components not readily adaptable to commercially available, standard detachable nut type fittings.
U.S. Pat. No. 5,222,768, entitled "Fluid Line Nut Locking Device," having common inventors with the present application, and assigned to Micron Technology, Inc. describes a very worthwhile device for locking fluid line valves. The above cited patent is ideally suited for new installation of transmission lines and valves.
However, there are a great many valves and fluid transmission lines already installed in semiconductor fabs throughout the world. It is a very difficult and cumbersome task to disassemble the fluid lines, drain the fluids, install a valve lock, and then, have the lines requalified for use in the manufacturing process. Thus, there exists a tremendous need to have a fluid line nut locking device that is capable of being retrofitted to the transmission lines already in place in existing semiconductor fabs.